Transmission and retransmission of data to or from a mobile station, MS, or user equipment, UE, is previously known. It is also known to use medium access control and radio link control layers of a UMTS protocol structure in acknowledged mode for dedicated channels.
In acknowledged mode, retransmissions are undertaken in case of detected transmission errors not recovered by forward error control. This is also called automatic repeat request, ARQ. With ARQ, retransmissions can be undertaken unless a transmitted message is (positively) acknowledged or if it is negatively acknowledged. Generally there are time limits for the respective positive and negative acknowledgements to be considered.
Within this patent application, a radio network controller, RNC, is understood as a network element including a radio resource controller. Node B is a logical node responsible for radio transmission/reception in one or more cells to/from a User Equipment. A base station, BS, is a physical entity representing Node B.
Medium access control, MAC, and radio link control, RLC, is used within radio communications systems like General Packet Radio Services, GPRS, and UMTS.
With reference to FIG. 1, Node B1 and Node B2 of a radio communications system are logical nodes responsible for radio transmission/reception in one or more cells to/from the User Equipment UE. BS1 and BS2 are physical entities representing Node B1 and Node B2 respectively. Node B1 and Node B2 terminate the air interface, called Uu interface within UMTS, between UE and respective Node B towards the radio network controller RNC. In UMTS the interface between a Node B and an RNC is called Iub interface.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical Layer Procedures, 3G TS 25.301 v3.6.0, France, September 2000, specifies in chapter 5 Radio Interface Protocol Architecture of a UMTS system. There are three protocol layers:                physical layer, layer 1 or L1,        data link layer, layer 2 or L2, and        network layer, layer 3 or L3.        
Layer 2, L2, and layer 3, L3 are divided into Control and User Planes. Layer 2 consists of two sub-layers, RLC and MAC, for the Control Plane and four sub-layers, BMC, PDCP, RLC and MAC, for the User Plane. The acronyms BMC, PDCP, RLC and MAC denote Broadcast/Multicast Control, Packet Data Convergence Protocol, Radio Link Control and Medium Access Control respectively.
FIG. 2 illustrates a simplified UMTS layers 1 and 2 protocol structure for a Uu Stratum, UuS, or Radio Stratum, between a user equipment UE and a Universal Terrestrial Radio Access Network, UTRAN.
Radio Access Bearers, RABs, make available radio resources (and services) to user applications. For each mobile station there may be one or several RABs. Data flows (in the form of segments) from the RABs are passed to respective Radio Link Control, RLC, entities which amongst other tasks buffer the received data segments. There is one RLC entity for each RAB. In the RLC layer, RABs are mapped onto respective logical channels. A Medium Access Control, MAC, entity receives data transmitted in the logical channels and further maps logical channels onto a set of transport channels. In accordance with subsection 5.3.1.2 of the 3GPP technical specification, MAC should support service multiplexing e.g. for RLC services to be mapped on the same transport channel. In this case identification of multiplexing is contained in the MAC protocol control information.
Transport channels are finally mapped to a single physical channel which has a total bandwidth allocated to it by the network. In frequency division duplex mode, a physical channel is defined by code, frequency and, in the uplink, relative phase (I/Q). In time division duplex mode a physical channel is defined by code, frequency, and time-slot. The DSCH, e.g., is mapped onto one or several physical channels such that a specified part of the downlink resources is employed. As further described in subsection 5.2.2 of the 3GPP technical specification the L1 layer is responsible for error detection on transport channels and indication to higher layer, FEC encoding/decoding and interleaving/deinterleaving of transport channels.
PDCP provides mapping between Network PDUs (Protocol Data Units) of a network protocol, e.g. the Internet protocol, to an RLC entity. PDCP compresses and decompresses redundant Network PDU control information (header compression and decompression).
For transmissions on point-to-multipoint logical channels, BMC stores at UTRAN-side Broadcast Messages received from an RNC, calculates the required transmission rate and requests for the appropriate channel resources. It receives scheduling information from the RNC, and generates schedule messages. For transmission, the messages are mapped on a point-to-multipoint logical channel. At the UE side, BMC evaluates the schedule messages and deliver Broadcast Messages to upper layer in the UE.
3G TS 25.301 also describes protocol termination, i.e. in which node of UTRAN the radio interface protocols are terminated, or equivalently, where within UTRAN the respective protocol services are accessible.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical Layer Procedures, 3G TS 25.322 v3.5.0, France, December 2000, specifies the RLC protocol. The RLC layer provides three services to the higher layers:                transparent data transfer service,        unacknowledged data transfer service, and        acknowledged data transfer service.        
In subsection 4.2.1.3 an acknowledged mode entity, AM-entity, is described (see FIG. 4.4 of the 3GPP Technical Specification). In acknowledged mode automatic repeat request, ARQ, is used. The RLC sub-layer provides ARQ functionality closely coupled with the radio transmission technique used.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical channels and mapping of transport channels onto physical channels (FDD), 3G TS 25.211 v4.6.0, France, September 2002, describes characteristics of the Layer 1 transport channels and physicals channels in the FDD mode of UTRA. Chapter 4 describes dedicated and common transport channels, such as                Dedicated Channel, DCH;        
Broadcast Channel, BCH;                Forward Access Channel, FACH;        Paging Channel, PCH;        Random Access Channel, RACH;        Common Packet Channel, CPCH; and        Downlink Shared Channel, DSCH.        
Chapter 5 defines a radio frame and a slot on the physical channel according to the 3GPP technical specification:                A radio frame is a processing duration, which consists of 15 slots. The length of a radio frame corresponds to 38400 chips.        A slot is a duration, which consists of fields containing bits. The length of a slot corresponds to 2560 chips.        
The specification defines two uplink dedicated physical channels:                uplink Dedicated Physical Data Channel, uplink DPDCH; and        uplink Dedicated Physical Control Channel, uplink DPCCH.        
The 3GPP technical specification explains,                “The uplink DPDCH is used to carry the DCH transport channel. There may be zero, one, or several uplink DPDCHs on each radio link.        The uplink DPCCH is used to carry control-information generated at Layer 1. The Layer 1 control information consists of known pilot bits to support channel estimation for coherent detection, transmit power-control (TPC) commands, feedback information (FBI), and an optional transport-format combination indicator (TFCI). The transport-format combination indicator informs the receiver about the instantaneous transport format combination of the transport channels mapped to the simultaneously transmitted uplink DPDCH radio frame. There is one and only one uplink DPCCH on each radio link.”        
FIG. 3 illustrates the frame structure for uplink DPDCH and DPCCH. In downlink direction DPDCH and DPCCH are time division multiplexed.
The frame structure of uplink data and control parts associated with CPCH is similar to that of uplink DPDCH and uplink DPCCH respectively.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Multiplexing and channel coding (FDD), 3G TS 25.212 v5.0.0, France, March 2002, describes the characteristics of the Layer 1 multiplexing and channel coding in the FDD mode of UTRA. Section 4.3 describes transport format detection. For a Coded Composite Transport Channel (CCTrCH), if the transport format set, TFS, of a Transport Channel, TrCH, contains more than one transport format, the transport format can be detected either by signaling the particular transport format using the TFCI field, by blindly detecting the transport format by use of channel decoding and CRC check or using guided detection from at least one other guiding TrCH.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Radio Resource Control (RRC), Protocol Specification, 3G TS 25.331 v4.7.0, France, September 2002, specifies the RRC protocol for the UE-UTRAN interface. Section 10.3.5.11 describes in tabular format Transport Channel, TrCH, Information Elements of RRC messages related to semi-static transport format information, TFI, including transmission time interval, TTI. TTI is the duration of data over which coding and interleaving is performed for a certain transport channel. According to the 3GPP technical specification, TTI is one of 10, 20, 40 and 80 ms. Section 10.3.5.80 describes transport format combination, TFC, control duration, defining a period in multiples of 10 ms frames for which the defined TFC sub-set is to be applied. Section 10.3.6.81 describes a Transport Format Combination Indicator, TFCI, combining indicator, indicating by TRUE or FALSE whether a part of TFCI, TFCI2, should be softly combined with other TFCI2 parts of the combining set. Section 10.3.6 describes corresponding Physical Channel, PhyCH or PhCH, Information Elements as applicable.
None of the cited documents above discloses a method and system of compatibly extending an existing channel structure for the radio interface adapting a static or semi-static transmission interval such that alternating TTI could be adopted to a data channel. Further, it is not revealed a method and system such that whether or not this extension is made use of could be blindly detected, not requiring additional signaling.